fix(PerformanceResourceTiming): clarify startTime is not always fetchStart - #45544
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fix(PerformanceResourceTiming): clarify startTime is not always fetchStart#45544BaconMan1168 wants to merge 1 commit into
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…Start The startTime bullet claimed the value is equivalent to fetchStart, which contradicted the timestamp diagram below it. The two only coincide when there are no HTTP redirects, since fetchStart is the time immediately before the final resource in the redirection is fetched.
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Description
The
PerformanceEntry.startTimebullet on thePerformanceResourceTimingpage stated that the value is equivalent toPerformanceResourceTiming.fetchStart. It now explains that the two are equal only when there are no HTTP redirects.Motivation
The claim contradicted the timestamp diagram directly below it, which places
startTimebefore the redirect phase andfetchStartafter it. Readers had no way to tell which one was right.Per the Resource Timing spec, a resource entry's
startTimecomes from the fetch timing info's start time, whilefetchStartreturns the post-redirect start time, so the values diverge as soon as a redirect is involved. The new text reuses the redirect caveat already documented on thefetchStartsubpage.Additional details
fetchStartgetter steps are to convert fetch timestamp for this's timing info's post-redirect start time")files/en-us/web/api/performanceresourcetiming/fetchstart/index.mdRelated issues and pull requests
Fixes #43903